SMAPI support for Linux

ThinkPad laptops include a proprietary interface called SMAPI BIOS (System Management Application Program Interface) which provides some hardware control functionality that is not exposed by any other interface (e.g., ACPI).

The SMAPI interfaces changes a lot between models, and is poorly documented, so Linux support is not exhaustive for most models. There are currently two SMAPI access mechanisms available: thinkpad and tpctl for older ThinkPads, and tp_smapi for newer ones.

ATTENTION!

These drivers use undocumented features and direct hardware access. They thus cannot be guaranteed to work, and may cause arbitrary damage (especially on models they weren't tested on).

Using the tp_smapi module

The tp_smapi kernel module exposes some features of the SMAPI BIOS found on recent ThinkPads via a sysfs interface. Currently, the implemented functionality is control of battery charging (this is useful for increasing battery lifetime or for using a leftover under-spec power supply that can't handle the combined power draw of running and charging), and control of CD/DVD speed.

• Project page: http://tpctl.sourceforge.net/
• You need to donwnload only the tp_smapi kernel module.

Installation

To compile and load the module:

# tar xzvf tp_smapi-0.10.tgz
# cd tp_smapi-0.10
# make load

To install permanently (optional):

# make install
# modprobe tp_smapi

Battery charge control features

To set the thresholds for starting and stopping battery charging (in percent of current full charge capacity):

# echo 40 > /sys/devices/platform/smapi/BAT0/start_charge_thresh
# echo 70 > /sys/devices/platform/smapi/BAT0/stop_charge_thresh
# cat /sys/devices/platform/smapi/BAT0/*_charge_thresh
40 
70

To unconditionally inhibit charging for 17 minutes:

# echo 17 > /sys/devices/platform/smapi/BAT0/inhibit_charge_minutes

To cancel charge inhibiting:

# echo 0 > /sys/devices/platform/smapi/BAT0/inhibit_charge_minutes

Battery status features

To view exteded battery status (see below about conflict with hdaps):

# cat /sys/devices/platform/smapi/BAT0/installed
# cat /sys/devices/platform/smapi/BAT0/state       # idle/charging/discharging
# cat /sys/devices/platform/smapi/BAT0/cycle_count 
# cat /sys/devices/platform/smapi/BAT0/current_now # instantaneous current
# cat /sys/devices/platform/smapi/BAT0/current_avg # last minute average
# cat /sys/devices/platform/smapi/BAT0/power_now   # instantaneous power
# cat /sys/devices/platform/smapi/BAT0/power_avg   # last minute average
# cat /sys/devices/platform/smapi/BAT0/last_full_capacity
# cat /sys/devices/platform/smapi/BAT0/remaining_capacity
# cat /sys/devices/platform/smapi/BAT0/design_capacity
# cat /sys/devices/platform/smapi/BAT0/voltage
# cat /sys/devices/platform/smapi/BAT0/design_voltage
# cat /sys/devices/platform/smapi/BAT0/manufacturer
# cat /sys/devices/platform/smapi/BAT0/model
# cat /sys/devices/platform/smapi/BAT0/serial
# cat /sys/devices/platform/smapi/BAT0/barcoding
# cat /sys/devices/platform/smapi/BAT0/chemistry
# cat /sys/devices/platform/smapi/ac_connected

The raw status data, including some fields not in the above (in case you can figure them out):

# cat /sys/devices/platform/smapi/BAT0/dump  

In all of the above, replace BAT0 with BAT1 to address the 2nd battery.

Optical drive control features

To control the speed of the optical drive:

ATTENTION!

Changing the CD speed simultaneously with a read or write to the CD will hang your computer. The hdparm -E or eject -x commands might also work for you, and are safer (but have no effect for DVD on some models, such as ThinkPad 43).

# echo 0 yes_crash_my_computer > /sys/devices/platform/smapi/cd_speed # slow
# echo 1 yes_crash_my_computer > /sys/devices/platform/smapi/cd_speed # medium
# echo 2 yes_crash_my_computer > /sys/devices/platform/smapi/cd_speed # fast
# cat /sys/devices/platform/smapi/cdrom_speed
2

Other features

Other things that can be controlled through SMAPI, but are not supported in this version of the driver, include forcing battery discharge, PCI bus power saving, CPU power saving control and fan control. See the included README file for more information.

Conflict with hdaps

The extended battery status function conflicts with the hdaps kernel module (they use the same IO ports). If you load hdaps first, tp_smapi will disable its battery status functions (and log a message in the kernel log). If you load tp_smapi first, hdaps will refuse to load. Use rmmod to switch between the two.

Some of the battery status is also visible through ACPI (/proc/acpi/battery/*).

The charging control files (*_charge_thresh and inhibit_charge_minutes) don't have this problem.

Model-specific status

tp_smapi feature support matrix

×	start_charge_thresh	stop_charge_thresh	inhbit_charge_minutes	cdrom_speed	battery status files (see notice about hdaps above)
G41	yes	no	yes	yes	unknown
R40	no	no	no	yes	unknown
R50p	no	no	no	yes	unknown
R51	yes	no	yes	unknown	unknown
R52	yes	yes	yes	yes	unknown
T40	no	no	no	yes	unknown
T40p	no	no	no	yes	yes
T41	yes	no	yes	unknown	unknown
T41p	no	no	no	yes	unknown
T42	yes	unknown	unknown	yes	unknown
T42p	yes	no	yes	unknown	unknown
T43	yes	yes	yes	yes	yes
T43p	yes	yes	yes	yes	yes
X31	no	no	no	unknown	yes
X32	no	no	no	unknown	unknown
X40	yes	no	yes	unknown	yes
X41	yes	yes	yes	unknown	unknown

Please update the above and report your experience on the discussion page. If the module loads but gives a "not supported" or "not implementeded" when you try to use some specific file in /sys/devices/platform/smapi/, please report the dmesg output and whether the corresponding functionality is available under Windows - maybe your ThinkPad just can't do that.

Using the thinkpad module

This solution consists of a module, called thinkpad, and a user-space tool caled tpctl. It provides very rich functionality for older ThinkPads, but on newer ThinkPads much of this functionality is exposed and supported through an ACPI interface and the SMAPI access does not work anymore. Kernel 2.6.9 and newer is unsupported; for kernel 2.6.3 and newer you need tpctl >=4.14 and thinkpad >=5.5. For details, see the README and list of supported models.

• Project page: http://tpctl.sourceforge.net/
• You need to download the thinkpad module and tpctl userspace tool.
• There is also an optional GUI: configure-thinkpad.